Live aquatic animals, such as lobster, crab, crayfish, shellfish, urchins, and fish, are sold in many countries throughout the world. In retail stores, as well as restaurants, the aquatic animals are kept in large tanks of water that is constantly circulated and filtered. The tanks can hold up to several layers of animals on the bottom. When a customer desires to purchase a lobster, for example, or a cook needs to select one, an attendant must reach into the tank with his hand or an instrument such as a net to remove the animal. Sometimes this process is repeated when a customer changes his mind or the attendant selects tile wrong animal. Thus, the amount of attendant time and consequently incremental cost is relatively large. Another problem with this arrangement is that many times the attendants are constantly putting their arms in the water. Crustaceans, as well as the bacteria that are used to filter the crustaceans' waste from the water, are very sensitive to impurities such as soaps and colognes that may be on the skin. Thus, such constant exposure may kill tile bacteria, which inevitably also kills the crustaceans, requiring not only the replacement of the crustaceans but the filtration media with the bacteria as well.
Shellfish such as clams and mussels are often kept on a bed of ice for retail display. The fresh water ice is actually toxic to the marine shellfish and thus slowly kills them. In addition, the shellfish dry out as they sit on the ice, reducing the market value and shortening the product life. Further, like other aquatic animals, the shellfish must be manually retrieved and weighed for retail sale. Accordingly, the cost of displaying and selling aquatic animals such as crustaceans and shellfish is so high that many operations do not make money on the sale.